404 error /cannot delete the old index.html file in www

Hello All,

I am new to Omeka, and am trying to install Omeka 2.0 on my Ubuntu laptop by following the instructions given at:
However, I have had 2 problems: 1) After doing everything in the first step(et up LAMP server + Unzip + ImageMagick), I still get a 404 error on my URL
2) In the 3rd part of step 2,when I try to delete the old index.html file in www, it says that there is "no such file or directory". why is that?

Thank you very much,